JP4910684B2 - Epoxy resin composition for fiber reinforced composite materials - Google Patents

Description

  The present invention relates to an epoxy resin composition for fiber-reinforced composite materials.

Fiber reinforced composite materials using an epoxy resin composition as a matrix resin are widely used in aircraft, automobiles, and industrial applications because of their excellent mechanical properties. In particular, in aircraft structural materials and interior materials, cases of using fiber-reinforced composite materials as face plates for honeycomb panels are increasing from the viewpoint of weight reduction.
In recent years, a so-called self-adhesion technique for directly bonding a honeycomb core and a prepreg has been demanded with the aim of further reducing the weight of the honeycomb panel and reducing the molding cost.
In order to make the prepreg exhibit self-adhesiveness, the joint surface between the honeycomb core and the prepreg is wetted with the resin of the prepreg at the time of heat curing to form a resin pool called a so-called fillet.
Patent Document 1 combines high toughness, high extensibility, and low internal stress, high strength, high elastic modulus, low water absorption, high heat resistance, good workability, and high stability of these properties. For the purpose of providing a thermosetting resin composition, a cured product, and a prepreg and a fiber reinforced plastic using the same as a matrix resin, the following components [A], [B], and [C] are essential, and the configuration Resin composition in which element [C] is a block copolymer or graft copolymer composed of a chain compatible with component [A] or [B] and an incompatible chain [A]: thermosetting resin [B]: Curing agent, [C]: Thermoplastic resin ”have been proposed.

JP-A-2-305860

However, when the present inventors use a composition as described in Patent Document 1 as a matrix resin for a prepreg and directly bond the honeycomb and the prepreg, the strength of the fillet formed is low, and the cured product We found that toughness is low.
The fillet is formed in a state in which the resin hangs or rises along the honeycomb wall in the thickness direction of the honeycomb core from the prepreg, and its shape is closely related to the viscosity of the resin, and the strength of the fillet constitutes the prepreg. It depends on the toughness of the matrix resin.
Then, an object of this invention is to provide the epoxy resin composition for fiber reinforced composite materials which can become a hardened | cured material with high toughness.

  As a result of earnest research to solve the above problems, the present inventors have found that a cured product obtained by curing an epoxy resin composition containing a specific epoxy resin, a thermoplastic resin, and a curing agent is a specific product. The present invention was completed by finding that it has a morphology and high toughness.

That is, the present invention provides the following (1) to (19).
(1) Using an epoxy resin (a1) having a weight average molecular weight of 1,000 or less, an epoxy resin (a2) having a weight average molecular weight of 10,000 to 100,000, and a curing agent (C),
An epoxy resin (a3) obtained by pre-reacting a part of the epoxy resin (a1), a part or all of the epoxy resin (a2) and a part of the curing agent (C), and the epoxy An epoxy resin (A) containing the remainder of the resin (a1);
A thermoplastic resin (B);
Containing the remainder of the curing agent (C),
The epoxy resin composition for fiber-reinforced composite materials, wherein the cured form has a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and / or a continuous phase of the thermoplastic resin (B).
(2) The epoxy resin (A) further includes a trifunctional or higher functional epoxy resin (a4),
The fiber according to (1), wherein the amount of the epoxy resin (a4) is 30 to 90 parts by mass in 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). Epoxy resin composition for reinforced composite materials.
(3) used in the preliminary reaction,
The amount of a part of the epoxy resin (a1) is 2 to 20 parts by mass in 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3),
A part or all of the epoxy resin (a2) is 2 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3).
A part of the curing agent (C) is used in an amount of 0.2 of the epoxy group contained in a part of the epoxy resin (a1) and a part or all of the epoxy resin (a2) used in the preliminary reaction. The epoxy resin composition for fiber-reinforced composite materials according to the above (1) or (2), which is an amount corresponding to ˜0.4 equivalent.
(4) In any one of the above (1) to (3), the molecular skeleton of the epoxy resin (a2) is at least one selected from the group consisting of bisphenol A type, bisphenol F type, and copolymers thereof. The epoxy resin composition for fiber-reinforced composite materials described.
(5) The above (1), wherein the remaining amount of the epoxy resin (a1) is 1 to 68 parts by mass in 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). The epoxy resin composition for fiber-reinforced composite materials according to any one of) to (4).
(6) The amount obtained by removing the epoxy resin (a2) used in the preliminary reaction from the epoxy resin (a2) is 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). The epoxy resin composition for fiber-reinforced composite materials according to any one of (1) to (5), which is 0 to 18 parts by mass relative to the mass.
(7) The amount of the epoxy resin (a3) used in the preliminary reaction excluding a part of the curing agent (C) is an epoxy resin excluding the epoxy resin (a2) and the epoxy resin (a3) ( A) The epoxy resin composition for fiber-reinforced composite materials according to any one of the above (1) to (6), which is 4 to 40 parts by mass with respect to 100 parts by mass.
(8) The epoxy resin composition for a fiber-reinforced composite material according to any one of (1) to (7), wherein the thermoplastic resin (B) has a reactive functional group at a molecular end.
(9) The thermoplastic resin (B) is a polyethersulfone resin particle and / or a polyetherimide resin particle, and the average particle diameter of the particles is 200 μm or less. The epoxy resin composition for fiber-reinforced composite materials according to any one of the above.
(10) The amount of the thermoplastic resin (B) is 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3) ( The epoxy resin composition for fiber-reinforced composite materials according to any one of 1) to (9).
(11) The above-mentioned curing agent (C) used in the epoxy resin composition for fiber-reinforced composite material according to any one of (1) to (10) above is diaminodiphenyl sulfone and / or a latent curing agent. The epoxy resin composition for fiber-reinforced composite materials according to any one of (1) to (10).
(12) The above (1), wherein the amount of the curing agent (C) is 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). The epoxy resin composition for fiber-reinforced composite materials according to any one of (1) to (11).
(13) The epoxy resin composition for fiber-reinforced composite materials according to any one of the above (1) to (12), wherein the minimum viscosity by dynamic viscoelasticity measurement at a heating rate of 2 ° C./min is 10 to 150 Pa · s. object.
(14) The fiber-reinforced composite according to any one of (1) to (13), wherein a fracture toughness value measured in accordance with ASTM D5045-99 after curing is 2.0 MPa · m ^1/2 or more. Epoxy resin composition for materials.
(15) A fiber-reinforced prepreg obtained by combining the epoxy resin composition for fiber-reinforced composite material according to any one of (1) to (14) above with a reinforcing fiber as a matrix resin.
(16) The fiber reinforced prepreg according to the above (15), wherein the content of the matrix resin is 30 to 50% by mass in the fiber reinforced prepreg.
(17) The fiber-reinforced prepreg according to the above (15) or (16), wherein the reinforcing fiber is a carbon fiber.
(18) A honeycomb sandwich panel obtained by laminating and curing the fiber-reinforced prepreg according to any one of (15) to (17) above and a honeycomb core.
(19) The honeycomb sandwich panel according to (18), wherein the honeycomb core is at least one selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.

  The epoxy resin composition for fiber-reinforced composite materials of the present invention can be a cured product with high toughness.

The present invention will be described in detail below.
First, the epoxy resin composition for fiber-reinforced composite materials of the present invention will be described.
The epoxy resin composition for fiber-reinforced composite material of the present invention is
Using an epoxy resin (a1) having a weight average molecular weight of 1,000 or less, an epoxy resin (a2) having a weight average molecular weight of 10,000 to 100,000, and a curing agent (C),
An epoxy resin (a3) obtained by pre-reacting a part of the epoxy resin (a1), a part or all of the epoxy resin (a2) and a part of the curing agent (C), and the epoxy An epoxy resin (A) containing the remainder of the resin (a1);
A thermoplastic resin (B);
Containing the remainder of the curing agent (C),
The cured form is a composition having a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and / or a continuous phase of the thermoplastic resin (B).
Hereinafter, this may be referred to as “the composition of the present invention”.

The composition of the present invention comprises:
Using an epoxy resin (a1) having a weight average molecular weight of 1,000 or less, an epoxy resin (a2) having a weight average molecular weight of 10,000 to 100,000, and a curing agent (C),
An epoxy resin (a3) obtained by pre-reacting a part of the epoxy resin (a1), a part or all of the epoxy resin (a2) and a part of the curing agent (C), and the epoxy An epoxy resin (A) containing the remainder of the resin (a1);
A thermoplastic resin (B);
And the remainder of the curing agent (C).

The composition of the present invention uses an epoxy resin (a1) having a weight average molecular weight of 1,000 or less and a curing agent (C) as a raw material for the preliminary reaction of the epoxy resin (a3) and a component of the composition. The epoxy resin (a2) having a molecular weight of 10,000 to 100,000 is used as a raw material for the preliminary reaction and a component of the composition, or a raw material for the preliminary reaction.
The epoxy resin (a1) used in the composition of the present invention is divided into a part used in the preliminary reaction and a part used as a component of the composition.
In addition, the epoxy resin (a2) used in the composition of the present invention can be partially or wholly used for the preliminary reaction, and when a part of the epoxy resin (a2) is used for the preliminary reaction, the present invention. The composition may contain the remainder of the epoxy resin (a2) as a component of the composition.
Moreover, the hardening | curing agent (C) used in the composition of this invention is divided and used for the part used by the preliminary reaction, and the part used as a component of a composition.
In the specification of the present application, “epoxy resin (a1) used in the composition of the present invention” means the combination of the amount used in the preliminary reaction and the component used as a component of the composition in the composition of the present invention. Means epoxy resin (a1).
The epoxy resin (a2) used in the composition of the present invention and the curing agent (C) used in the composition of the present invention are the same as the epoxy resin (a1) used in the composition of the present invention.

The amount of the epoxy resin (a2) used in the composition of the present invention is 100 masses of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3) from the viewpoint of maintaining tackiness and draping properties. The amount is preferably 2 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to parts.
“Epoxy resin (A) excluding epoxy resin (a2) and epoxy resin (a3)” refers to an epoxy resin (A) obtained by removing epoxy resin (a2) and epoxy resin (a3).
The amount of the curing agent (C) used in the composition of the present invention is such that the resulting cured product is excellent in strength and heat resistance required as a face plate, and has higher toughness, and the epoxy resin (a2) and It is preferable that it is 20-60 mass parts with respect to 100 mass parts of epoxy resins (A) except an epoxy resin (a3), and it is more preferable that it is 30-50 mass parts.
About the epoxy resin (a3) which the composition of this invention contains, the quantity which remove | excluded a part of hardening | curing agent (C) used in the preliminary reaction from an epoxy resin (a3) requires the hardened | cured material obtained as a faceplate. 4 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3) from the viewpoint of excellent strength and heat resistance, and higher toughness. Is preferable, and it is more preferable that it is 10-30 mass parts.
The amount of the thermoplastic resin (B) contained in the composition of the present invention is such that the viscosity can be optimized to form a fillet in a good shape, and the cured product has excellent tackiness and draping properties and higher toughness. From the viewpoint that it can be, it is preferably 20 to 60 parts by mass, and 30 to 50 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). Is more preferable.

The epoxy resin (A) will be described below.
The epoxy resin (A) contained in the composition of the present invention includes an epoxy resin (a1) and an epoxy resin (a3).
In addition, when the amount of the epoxy resin (a2) used in the preliminary reaction is a part of the total amount of the epoxy resin (a2) used in the composition of the present invention, the epoxy resin (A) further contains an epoxy resin ( a2) can be included.

The epoxy resin (a1) will be described below.
The epoxy resin (a1) contained in the epoxy resin (A) is not particularly limited as long as it is a compound having a weight average molecular weight of 1,000 or less and having two or more epoxy groups.

Examples of the epoxy resin (a1) include bisphenol A type, bisphenol F type (for example, bisphenol F type epoxy resin represented by the following formula (1)), brominated bisphenol A type, hydrogenated bisphenol A type, and bisphenol S. Type, epoxy compound having bisphenyl group such as bisphenol AF type, biphenyl type, polyalkylene glycol type, alkylene glycol type epoxy compound, epoxy compound having naphthalene ring, bifunctional type such as epoxy compound having fluorene group A glycidyl ether type epoxy resin, such as a phenol novolak type, an orthocresol novolak type, a trishydroxyphenylmethane type, a trifunctional type, and a tetraphenylol ethane type; Synthetic fatty acid glycidyl ester type epoxy resin such as imar acid; N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N An aromatic epoxy resin having a glycidylamino group such as N, diglycidylaniline; an epoxy compound having a tricyclo [5.2.1.0 ^2,6 ] decane ring; an alicyclic epoxy resin; An epoxy resin having a sulfur atom in the main chain of an epoxy resin represented by Flep 10; a urethane-modified epoxy resin having a urethane bond; a rubber-modified epoxy resin containing polybutadiene, liquid polyacrylonitrile-butadiene rubber or acrylonitrile butadiene rubber (NBR) Can be mentioned.

  Especially, the epoxy resin (a1) is preferably a bisphenol A type epoxy resin or a bisphenol F type epoxy resin from the viewpoint of workability and heat resistance of the cured product.

The weight average molecular weight of the epoxy resin (a1) is preferably 300 to 1,000, and more preferably 300 to 500, from the viewpoint that the composition is easily dissolved uniformly.
In the present invention, the weight average molecular weight is a value measured by GPC analysis.

The epoxy resin (a1) is preferably in the form of a liquid from the viewpoint that the composition can be easily dissolved uniformly and the viscosity of the composition can be within an appropriate range.
The viscosity at 25 ° C. of the epoxy resin (a1) is preferably 5 to 150 poise, and more preferably 5 to 100 poise.
In the present invention, the viscosity measurement method conforms to JIS K 6862.

  An epoxy resin (a1) can be used individually or in combination of 2 types or more, respectively.

Of the total amount of the epoxy resin (a1) used in the composition of the present invention, a part of the epoxy resin (a1) is used for the preliminary reaction.
The remainder of the epoxy resin (a1) contained as a component of the composition in the composition of the present invention (that is, the epoxy resin used in the preliminary reaction from the epoxy resin (a1) used in the composition of the present invention) From the viewpoint of increasing the affinity of the phase separation interface, the amount excluding (a1) is the sum of the epoxy resin (a2) (that is, the amount used for the preliminary reaction and the amount used as a component of the composition). .) And the epoxy resin (A) excluding the epoxy resin (a3) (wherein the epoxy resin (A) includes at least an epoxy resin (a1) and an epoxy resin (a4) which can be included as necessary). ) It is preferably 1 to 68 parts by mass in 100 parts by mass, and more preferably 20 to 50 parts by mass.

The epoxy resin (a3) will be described below.
The epoxy resin (a3) contained in the epoxy resin (A) is a preliminary reaction of a part of the epoxy resin (a1), a part or all of the epoxy resin (a2), and a part of the curing agent (C). Is an epoxy resin obtained.

The epoxy resin (a1) used in the preliminary reaction has the same meaning as described above.
Of these, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable from the viewpoint of workability and heat resistance of the cured product.
The epoxy resin (a1) used in the preliminary reaction can be used alone or in combination of two or more.
The epoxy resin (a1) used in the preliminary reaction may be the same as or different from the epoxy resin (a1) contained in the composition of the present invention. From the viewpoint of increasing the affinity of the phase separation interface, The epoxy resin (a1) used is preferably the same type as the epoxy resin (a1) contained in the composition of the present invention.

  Moreover, it is preferable that the weight average molecular weights of the epoxy resin (a1) used in a preliminary reaction are 300-1,000 from a viewpoint that it is easy to melt | dissolve uniformly with respect to an epoxy resin (a2), 300-1,000. More preferably, it is 500.

  The amount of the epoxy resin (a1) used in the preliminary reaction is such that the epoxy resin (a3) and the epoxy resin (a2) (epoxy resin (a2) are used in the preliminary reaction from the viewpoint of maintaining tackiness and draping properties. And the epoxy resin (A) excluding (as a total of the components used as components of the composition) (wherein the epoxy resin (A) is at least an epoxy resin (a1), an epoxy that can be included as necessary) Including 100 parts by mass of resin (a4)) It is preferably 2 to 20 parts by mass, and more preferably 5 to 15 parts by mass.

The epoxy resin (a2) will be described below.
The epoxy resin (a2) used in the preliminary reaction is not particularly limited as long as it is a compound having a weight average molecular weight of 10,000 to 100,000 and having two or more epoxy groups.

Examples of the molecular skeleton of the epoxy resin (a2) used in the preliminary reaction include bisphenol A type, bisphenol F type, and copolymers thereof.
The molecular skeleton of the epoxy resin (a2) used in the preliminary reaction is at least selected from the group consisting of bisphenol A type, bisphenol F type and copolymers thereof from the viewpoint of easy mixing with the epoxy resin (a1). One type is preferred.

  The weight average molecular weight of the epoxy resin (a2) used in the preliminary reaction is preferably 20,000 to 80,000 from the viewpoint that it can be a cured product having higher toughness, and is preferably 30,000 to 70,000. More preferably, it is 000.

The epoxy resin (a2) used in the preliminary reaction is preferably solid at room temperature from the viewpoint that it can be a cured product with higher toughness.
The epoxy resin (a2) used in the preliminary reaction preferably has a softening point of 130 ° C. or higher from the viewpoint of increasing toughness.

  The epoxy resin (a2) used in the preliminary reaction can be used alone or in combination of two or more.

The preliminary reaction is carried out using part or all of the total amount of the epoxy resin (a2) used in the composition of the present invention.
When a part of the total amount of the epoxy resin (a2) used in the composition of the present invention is used in the preliminary reaction, the viewpoint that the amount of the epoxy resin (a2) used in the preliminary reaction does not hinder toughness improvement. From 65 to 95% by mass of the total amount of the epoxy resin (a2) used in the composition of the present invention is preferable, and 70 to 90% by mass is more preferable.

  The amount of the epoxy resin (a2) used in the preliminary reaction is such that the epoxy resin (a3) and the epoxy resin (a2) (epoxy resin (a2) are used in the preliminary reaction from the viewpoint of maintaining tackiness and draping properties. And the amount used as a component of the composition.) (Wherein the epoxy resin (A) is at least the epoxy resin (a1) used in the composition of the present invention, The epoxy resin (a4) that can be included as necessary is included.) It is preferably 2 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to 100 parts by mass.

  The amount of the epoxy resin (a2) used in the preliminary reaction is 50 to 150 masses with respect to 100 parts by mass of the epoxy resin (a1) used in the preliminary reaction from the viewpoint that the toughness of the cured product can be further increased. Part is preferable, and 70 to 130 parts by mass is more preferable.

The curing agent (C) will be described below.
The curing agent (C) used in the preliminary reaction is not particularly limited as long as it can react with the epoxy resin.
For example, polyamine, imidazole compound, tetramethylguanidine, thiourea addition amine, polyamide, polyol, polymercaptan, polycarboxylic acid, acid anhydride, carboxylic acid hydrazide, carboxylic acid amide, polyphenol compound, novolak resin, latent curing agent Can be mentioned.
Polyamines and latent curing agents can be mentioned as preferred embodiments.

  The polyamine as the curing agent (C) used in the preliminary reaction is not particularly limited as long as it is a compound having two or more amino groups and / or imino groups. Examples include aliphatic polyamines, alicyclic polyamines, aromatic polyamine curing agents, and dicyandiamide. Of these, aromatic polyamine curing agents are preferred from the viewpoints of heat resistance, mechanical strength, and storage stability.

The aromatic polyamine curing agent is not particularly limited as long as two or more amino groups and / or imino groups are bonded to the aromatic ring. For example, 3,3′-diaminodiphenylsulfone (3,3′-DDS), diaminodiphenylsulfone such as 4,4′-diaminodiphenylsulfone (4,4′-DDS), diaminodiphenyl ether (DADPE), bisaniline, Benzyldimethylaniline, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4,4'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4 ' -Diaminodiphenylmethane, 2,2'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2 , 3-tolylenediamine, , 4-tolylenediamine, 2,5-tolylenediamine, 2,6-tolylenediamine, 3,4-tolylenediamine, methylthio diamine include diethyl toluene diamine.
Among these, 3,3′-diaminodiphenylsulfone (3,3′-DDS) is preferable from the viewpoint of being able to be cured by heating and improving the heat resistance of the cured product.

  The curing agent (C) used in the preliminary reaction is diaminodiphenyl sulfone and / or a latent curing agent from the viewpoint of higher toughness, higher fillet strength, and stronger self-adhesive strength of the fiber-reinforced prepreg. Is preferred.

  The latent curing agent is not particularly limited as long as it generates a curing agent by heat or the like, and the generated curing agent functions as a curing agent for the epoxy resin (A). Examples thereof include organic acid dihydrazide, dicyandiamide, amine imide, tertiary amine salt, imidazole salt, Lewis acid, Bronsted acid, oxazolidine compound, and ketimine compound.

  An oxazolidine compound is a compound having a saturated 5-membered heterocyclic ring containing oxygen and nitrogen and having an oxazolidine ring that opens in the presence of moisture (water). Specific examples include N-hydroxyalkyl oxazolidine and its polyisocyanate adduct, oxazolidine silyl ether, carbonate oxazolidine, ester oxazolidine and the like.

The ketimine compound is a compound having a ketimine bond derived from a ketone or aldehyde and an amine. In the present specification, the ketimine compound includes aldimine having a —HC═N bond.
The ketimine compound is not particularly limited. For example, obtained from methyl isobutyl ketone (MIBK) and propylene diamine; obtained from methyl isopropyl ketone (MIPK) and / or methyl-t-butyl ketone (MTBK) and Jeffamine EDR148; and MIPK and / or MTBK Obtained from 1,3BAC; obtained from MIPK and / or MTBK and norbornanediamine (NBDA); obtained from MIPK and / or MTBK and m-xylylenediamine (MXDA); MIPK and / or Those obtained from MTBK and polyamidoamine; those obtained from diethyl ketone and MXDA.

  The curing agent (C) used in the preliminary reaction can be used alone or in combination of two or more.

The amount of curing agent (C) used in the preliminary reaction is part of the curing agent (C) used in the composition of the present invention.
The amount of the curing agent (C) used in the preliminary reaction is an amount corresponding to 0.2 to 0.4 equivalent of the epoxy group of the epoxy resin (a1) and the epoxy resin (a2) used in the preliminary reaction. The amount is preferably equivalent to 0.25 to 0.35 equivalent.

The preliminary reaction will be described below.
In the composition of the present invention, the preliminary reaction is performed by reacting a part of the epoxy resin (a1), a part or all of the epoxy resin (a2), and a part of the curing agent (C), An epoxy resin (a3) is produced.
The preliminary reaction is a heating step in which a part of the epoxy resin (a1) and a part or all of the epoxy resin (a2) are heated to dissolve and / or disperse the epoxy resin (a1) and the epoxy resin (a2). And a step of generating an epoxy resin (a3) by adding a part of the curing agent (C) to the mixture of the compatible and / or dispersed epoxy resin (a1) and epoxy resin (a2) and reacting them by heating. One of preferred embodiments is provided with the following.

First, in the heating step, part of the epoxy resin (a1) and part or all of the epoxy resin (a2) are heated, so that the epoxy resin (a1) and the epoxy resin (a2) are compatible and / or dispersed. And a mixture of the epoxy resin (a1) and the epoxy resin (a2).
It is preferable that the temperature of a heating process is 80-120 degreeC from a viewpoint that an epoxy resin (a1) and an epoxy resin (a2) can fully be dissolved and / or disperse | distributed.
Heating is preferably performed with stirring.

Next, in the production step, a part of the curing agent (C) is added to the mixed and / or dispersed mixture of the epoxy resin (a1) and the epoxy resin (a2) and heated to react with the epoxy resin (a3). Is generated.
It is preferable that the temperature of a production | generation process is 130-170 degreeC from a reactive viewpoint with an epoxy resin (a1) and / or an epoxy resin (a2), and a hardening | curing agent (C).
Heating is preferably performed with stirring.
The reaction time is not particularly limited and is preferably 3 to 6 hours.

  An epoxy resin (a3) can be used individually or in combination of 2 types or more, respectively.

  The amount of the epoxy resin (a3) is the epoxy resin (a3) and the epoxy resin (a2) (the epoxy resin (a2) is used in the preliminary reaction from the viewpoint of achieving both toughness improvement, tackiness, and draping properties. And the epoxy resin (A) excluding at least the epoxy resin (a1) used in the composition of the present invention. Including epoxy resin (a4) that can be contained as necessary.) It is preferably 4 to 40 parts by mass, more preferably 15 to 25 parts by mass with respect to 100 parts by mass.

  When a part of the epoxy resin (a2) used in the composition of the present invention is used in the preliminary reaction, the epoxy resin (A) can further contain the epoxy resin (a2).

The epoxy resin (a2) has the same meaning as described above.
Among them, the molecular skeleton of the epoxy resin (a2) is bisphenol A type, bisphenol F type and these from the viewpoint that bisphenol A type epoxy resin and bisphenol F type epoxy resin are often used for the epoxy resin (a1). It is preferably at least one selected from the group consisting of these copolymers.

  The weight average molecular weight of the epoxy resin (a2) is preferably 20,000 to 80,000, more preferably 30,000 to 70,000, from the viewpoint of easily dissolving the composition uniformly. preferable.

Moreover, it is preferable that an epoxy resin (a2) is solid at room temperature from a viewpoint that it can become a hardened | cured material with higher toughness.
The softening point of the epoxy resin (a2) is preferably 130 ° C. or higher from the viewpoint of increasing the toughness.

  The epoxy equivalent of the epoxy resin (a2) is not completely compatible with the epoxy resin (A) before the composition is heat-cured, but is separated from the phase of the epoxy resin (A) after curing. From the viewpoint that it can be easily dissolved in the epoxy resin (A) at the time of heat-curing the composition, preferably from 1,000 to 8,000 g / eq, It is more preferably 000 to 6,000 g / eq. When the epoxy equivalent was 1,000 g / eq or more, the composition was not completely compatible with the epoxy resin (A) before being cured by heating, and separated into the epoxy resin (A) after curing. When an island phase (dispersed phase) can be formed and the epoxy equivalent is 8,000 g / eq or less, the composition can be easily dissolved in the epoxy resin (A) during heat curing of the composition.

  From the standpoint that the epoxy resin (a2) has an average particle size that is easily compatible with the epoxy resin (A) during heat curing, the viscosity of the composition can be adjusted appropriately, and the toughness becomes higher. It is preferable that it is 100 micrometers or less, and it is more preferable that it is 5-100 micrometers.

An epoxy resin (a2) can be used individually or in combination of 2 types or more, respectively.
Moreover, the epoxy resin (a2) that can be contained in the composition of the present invention may be the same as or different from the epoxy resin (a2) used in the preliminary reaction. Or it is preferable that it is the same kind from a viewpoint of being excellent in a dispersibility.

  The amount obtained by removing the epoxy resin (a2) used in the preliminary reaction from the epoxy resin (a2) used in the composition of the present invention (that is, the epoxy that can be contained as a component of the composition in the composition of the present invention) The amount of the resin (a2)) is excellent in toughness, and is improved in tackiness and draping properties. The epoxy resin (a3) and the epoxy resin (a2) (the epoxy resin (a2) is used in the preliminary reaction. And the amount used as a component of the composition.) (Wherein the epoxy resin (A) is at least the epoxy resin (a1) used in the composition of the present invention, Including epoxy resin (a4) that can be contained if necessary.) It is preferably 0 to 18 parts by mass with respect to 100 parts by mass. And more preferably 10 parts by weight.

In the composition of the present invention, the epoxy resin (A) preferably further contains a trifunctional or higher functional epoxy resin (a4) from the viewpoint of excellent heat resistance.
The epoxy resin (a4) will be described below.
The epoxy resin (a4) that the epoxy resin (A) can contain is not particularly limited as long as it is trifunctional or higher.

  For example, N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, triglycidyl-p-aminocresol, 1,3-bis Glycidylamine type epoxy resin such as (N, N-diglycidylaminomethyl) cyclohexane; Multifunctional glycidyl ether type such as phenol novolac type, orthocresol novolak type, trishydroxyphenylmethane type, tetraphenylolethane type An epoxy resin is mentioned.

  Among these, triglycidyl-p-aminophenol and triglycidyl-p-aminocresol are preferable from the viewpoint that the reinforcing fiber can be easily impregnated with the composition during the production of the fiber-reinforced prepreg.

  The weight average molecular weight of the epoxy resin (a4) is preferably 250 to 1,000, and more preferably 250 to 500, from the viewpoint that the composition is easily dissolved uniformly.

In addition, the epoxy resin (a4) is preferably in a liquid form from the viewpoint that the composition can be easily dissolved uniformly and the viscosity of the composition can be within an appropriate range.
The viscosity at 25 ° C. of the epoxy resin (a4) is preferably 5 to 50 poise, and more preferably 5 to 20 poise.

  An epoxy resin (a4) can be used individually or in combination of 2 types or more, respectively.

  The amount of the epoxy resin (a4) is from the viewpoint of maintaining fillet-forming properties, and the epoxy resin (a3) and the epoxy resin (a2) (the epoxy resin (a2) is used in the preliminary reaction and as a component of the composition. The epoxy resin (A) excluding (as a sum of the total amount of the components) (wherein the epoxy resin (A) includes at least the epoxy resin (a1) used in the composition of the present invention, if necessary). The epoxy resin (a4) which can be included is included.) It is preferable that it is 30-90 mass parts in 100 mass parts, and it is more preferable that it is 50-70 mass parts.

The thermoplastic resin (B) will be described below.
The thermoplastic resin (B) contained in the composition of the present invention is not particularly limited. For example, polyethersulfone resin, polyetherimide resin, polyimide resin, polyamide resin, polyether resin, polyester resin, polysulfone resin, polyamideimide resin, polyacrylate resin, polyaryl ether resin, polyphenyl ether resin, polyether ether ketone Resin.

Among these, polyethersulfone resins and polyetherimide resins are preferable from the viewpoint that the toughness of the cured product can be further increased.
Further, from the viewpoints of excellent compatibility with the epoxy resin (A), excellent compatibility with the epoxy resin (A), easy formation of a continuous phase, and higher toughness of the cured product, polyethersulfone resin can be obtained. Is preferred.

From the viewpoint that the thermoplastic resin (B) can be quickly and uniformly dissolved in the epoxy resin at the time of preparation of the composition, and large particles can be prevented from remaining undissolved, for example, powdery and particulate fine particles Is preferred.
The average particle diameter of the thermoplastic resin (B) is preferably 200 μm or less from the viewpoint that the dissolution in the epoxy resin (A) becomes uniform, the co-continuous phase is easily formed, and the toughness becomes higher. It is more preferable that the thickness is 5 to 80 μm.
The method in particular which makes a thermoplastic resin (B) fine particle is not restrict | limited, For example, a conventionally well-known thing is mentioned.
In the present invention, the average particle size of the thermoplastic resin (B) is measured by a particle size distribution measuring device.

  The thermoplastic resin (B) is a polyethersulfone resin particle and / or a polyetherimide resin particle, and one preferred embodiment is that the average particle diameter of the particle is 200 μm or less.

Moreover, it is preferable that a thermoplastic resin (B) has a reactive functional group in a molecular terminal from a viewpoint that the toughness of hardened | cured material can become higher.
Examples of the reactive functional group include a hydroxy group, a carboxy group, an amino group, an acid anhydride group, a mercapto group, and an isocyanate group.
Of these, a hydroxy group is preferred from the viewpoint of reactivity with the epoxy resin (A).
A thermoplastic resin (B) can be used individually or in combination of 2 types or more, respectively.

The amount of the thermoplastic resin (B) is an epoxy resin from the viewpoint that the viscosity can be optimized and the fillet can be formed in a good shape, and can be a cured product having excellent tackiness and draping properties and higher toughness. To 100 parts by mass of epoxy resin (A) excluding (a3) and epoxy resin (a2) (epoxy resin (a2) is the sum of the amount used in the preliminary reaction and the amount used as a component of the composition) It is preferable that it is 20-60 mass parts, and it is more preferable that it is 30-50 mass parts.
The amount of thermoplastic resin (B) is epoxy resin (A) excluding epoxy resin (a3) and epoxy resin (a2) (wherein epoxy resin (A) is used at least in the composition of the present invention). The epoxy resin (a1) and the epoxy resin (a4) that can be included as required are included.) When the amount is 20 parts by mass or more with respect to 100 parts by mass, the resulting cured product has a morphology of an epoxy resin (A ) And the thermoplastic resin (B).
When the amount of the thermoplastic resin (B) is 60 parts by mass or less with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a3) and the epoxy resin (a2), the tackiness and draping properties are excellent. Excellent workability of fiber reinforced prepreg.
Moreover, when the quantity of a thermoplastic resin (B) is 60 mass parts or less, the viscosity of a composition can be made low and it is excellent in workability | operativity.

The composition of the present invention contains a curing agent (C).
The curing agent (C) contained in the composition of the present invention is synonymous with the curing agent (C) used in the preliminary reaction.
Among them, the curing agent (C) contained in the composition of the present invention has higher toughness, higher fillet strength, and higher self-adhesive strength of the fiber-reinforced prepreg, and diaminodiphenyl sulfone and It is preferably a latent curing agent.
The latent curing agent has the same meaning as described above.
A hardening | curing agent (C) can be used individually or in combination of 2 types or more, respectively.
The curing agent (C) contained in the composition of the present invention may be the same as or different from the curing agent (C) used in the preliminary reaction, and the composition of the present invention contains from the viewpoint of improving compatibility. The curing agent (C) to be used and the curing agent (C) used in the preliminary reaction are preferably the same type.

  The remainder of the curing agent (C) contained in the composition of the present invention (that is, the amount obtained by removing the curing agent (C) used in the preliminary reaction from the curing agent (C) used in the composition of the present invention). From the standpoint that the obtained cured product is excellent in strength and heat resistance required as a face plate and has higher toughness, epoxy resins (A) and (A) excluding epoxy resin (a2) and epoxy resin (a3) (here The epoxy resin (A) contains at least the epoxy resin (a1) used in the composition of the present invention and the epoxy resin (a4) that can be included as necessary. It is preferably 20 to 60 parts by mass, and more preferably 30 to 50 parts by mass.

The composition of this invention contains an additive in the range which does not impair the effect of the composition of this invention other than an epoxy resin (A), a thermoplastic resin (B), and a hardening | curing agent (C). be able to.
Examples of the additive include a curing catalyst such as boron trifluoride / amine salt catalyst, solid rubber, filler, anti-aging agent, solvent, flame retardant, and pigment.

  Examples of the boron trifluoride / amine salt catalyst include boron trifluoride / monoethylamine, boron trifluoride / piperazine salt, and boron trifluoride / aniline salt.

  The solid rubber is not particularly limited as long as it is compatible with the epoxy resin (A), and examples thereof include acrylonitrile butadiene rubber and hydrogenated products thereof, acrylic rubber, ethylene-acrylic rubber, epichlorohydrin rubber, and ethylene-vinyl acetate rubber. Can be mentioned.

Examples of the filler include carbon black, calcium carbonate, titanium oxide, silica, and aluminum hydroxide.
Examples of the antiaging agent include hindered amines and hindered phenols.
Examples of the solvent include methanol, ethanol, propanol, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK).

  The composition of the present invention is not particularly limited for its production. For example, first, the epoxy resin (A) and the thermoplastic resin (B) are heated and dissolved to form a mixture, and the mixture is mixed with the curing agent (C). And a production method comprising a mixing step 2 to be obtained.

First, in the mixing step 1, the epoxy resin (A) and the thermoplastic resin (B) are heated and dissolved to form a mixture.
The epoxy resin (A) is, for example, a mixture of an epoxy resin (a1), an epoxy resin (a3), and an epoxy resin (a2) and an epoxy resin (a4) that can be included as necessary. Can be left as For example, the epoxy resin (a1), the epoxy resin (a3), and the epoxy resin (a2) and the epoxy resin (a4), which can be included as necessary, are individually added to the thermoplastic resin (B). Can be mixed in addition to.

95-180 degreeC is preferable and, as for the temperature at the time of dissolving an epoxy resin (A) and a thermoplastic resin (B), 100-130 degreeC is more preferable.
In addition, for example, it is preferable to mix with stirring for 0.5 to 3 hours until the mixture becomes uniform using a stirring device such as a planetary mixer.
From the viewpoint of the reactivity of the composition, it is preferable that the thermoplastic resin (B) is completely dissolved in the epoxy resin (A).

After mixing step 1, in mixing step 2, the curing agent (C) is added to the mixture and mixed to obtain a composition.
When the composition of this invention contains an additive, it is mentioned as one of the preferable aspects that an additive is added to a mixture in the mixing process 2. FIG.

In the mixing step 2, first, the mixture is preferably cooled to 60 to 100 ° C., more preferably 70 to 90 ° C., from the viewpoint that the increase in the viscosity of the composition can be suppressed.
Next, a hardening | curing agent (C) and the additive which can be used as needed are added and mixed with a mixture. The order in which each component is added is not particularly limited.
In mixing, it is preferable to heat to 70 to 90 ° C. to dissolve the components to obtain a uniform epoxy resin composition.
In addition, for example, it is preferable to mix with stirring for 0.5 to 3 hours until the mixture becomes uniform using a stirring device such as a planetary mixer.
By such a production method, the thermoplastic resin (B) is reliably dissolved, and the epoxy resin (a3) is uniformly dissolved and / or dispersed without unevenness, and a specific form is formed after curing to increase toughness. The self-adhesive strength of the fiber reinforced prepreg can be increased.

From the viewpoint that the composition of the present invention is excellent in productivity and self-adhesiveness of the fiber reinforced prepreg, the minimum viscosity by dynamic viscoelasticity measurement at a temperature rising rate of 2 ° C./min is 10 to 150 Pa · s. It is preferably 20 to 150 Pa · s. When it is 10 Pa · s or more, a good fillet can be formed, and self-adhesiveness is improved. When it is 150 Pa · s or less, while maintaining the formability of the fillet, the fiber is reinforced during the production of the fiber reinforced prepreg. The composition can be easily impregnated.
In the present invention, the minimum viscosity by dynamic viscoelasticity measurement is as follows: the composition of the present invention is used as a sample, the temperature is from 25 to 200 ° C., the heating rate is 2 ° C./min, the frequency is 10 rad / sec, and the strain is 1 % Of the complex viscosity in the dynamic viscoelasticity measurement in%.

The composition of the present invention is not particularly limited for its use.
For example, when the composition of the present invention is cured, the temperature is preferably 70 to 200 ° C, more preferably 120 to 180 ° C, from the viewpoint that the toughness of the cured product becomes higher.
Further, the pressure is preferably 1.5 to 4.0 kg / cm ² , more preferably 2.5 to 3.5 kg / cm ² from the viewpoint that the toughness of the cured product becomes higher.
The time is preferably 1 to 8 hours.

When the composition of the present invention is cured, the composition of the present invention is semi-cured and then further cured to obtain a cured product.
When the composition of the present invention is semi-cured, the temperature is preferably 50 to 200 ° C, more preferably 70 to 180 ° C, from the viewpoint that the toughness of the cured product becomes higher.
Further, the pressure is preferably 1.5 to 4.0 kg / cm ² , more preferably 2.5 to 3.5 kg / cm ² from the viewpoint that the toughness of the cured product becomes higher.
The time is preferably 1 to 8 hours.
Examples of the conditions for further curing after semi-curing include those described above.

The composition of the present invention becomes a cured product having a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and / or a continuous phase of the thermoplastic resin (B) after curing.
When the resulting cured product has a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B), both the epoxy resin (A) and the thermoplastic resin (B) form a continuous phase. ing.
Moreover, when a thermoplastic resin (B) becomes a continuous phase in the hardened | cured material obtained, an epoxy resin (A) becomes an island phase. That is, in such a case, the morphology of the cured product has an inverted sea island structure.
When the obtained cured product has a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and a continuous phase of the thermoplastic resin (B), the epoxy resin (A) and the thermoplastic resin are contained in the cured product. It means that a co-continuous phase with (B) and a continuous phase of the thermoplastic resin (B) exist respectively.

In the form after curing, the epoxy resin (a3) can be dissolved and / or dispersed in the epoxy resin (A).
When the epoxy resin (a3) is dispersed in the epoxy resin (A), the epoxy resin (a3) becomes an island phase using the epoxy resin (A) as a matrix resin.

  When the epoxy resin (a3) forms an island phase, the average particle diameter of the island phase is preferably 0.1 to 2 μm from the viewpoint that the toughness of the cured product becomes higher. More preferably, it is 5 μm.

The epoxy resin composition for fiber-reinforced composite material of the present invention has a co-continuous phase of epoxy resin (A) and thermoplastic resin (B) and / or a continuous phase of thermoplastic resin (B) after curing. Have. And the particle | grains of an epoxy resin (a3) can be disperse | distributed in an epoxy resin (A). The epoxy resin (a3) may be compatible with the epoxy resin (A).
When the epoxy resin (a3) is dispersed and / or compatible with the epoxy resin (A), the toughness of the cured product can be increased. By improving the toughness, the strength of the fillet is increased, and the self-adhesion strength of the fiber-reinforced prepreg can be increased.

The fracture toughness value measured in accordance with ASTM D5045-99 after curing the composition of the present invention is higher in the toughness of the cured product, and the face plate (fiber reinforced prepreg) and other members (eg, honeycomb core) From the viewpoint that it is possible to increase the peel strength in a peel test after self-adhesion strength with a), it is preferably 2.0 MPa · m ^1/2 or more, and 2.0 to 2.5 MPa · m ^1/2. It is more preferable that

  Examples of the use of the composition of the present invention include a matrix resin for fiber-reinforced prepreg.

Next, the fiber reinforced prepreg of the present invention will be described below.
The fiber-reinforced prepreg of the present invention is
The epoxy resin composition for fiber-reinforced composite material of the present invention is combined with reinforcing fibers as a matrix resin.

  The matrix composition used for the fiber-reinforced prepreg of the present invention is not particularly limited as long as it is the composition of the present invention.

  The reinforcing fiber used in the fiber-reinforced prepreg of the present invention is not particularly limited, and examples thereof include conventionally known fibers. Especially, it is preferable that it is at least 1 sort (s) chosen from the group which consists of carbon fiber, glass fiber, and an aramid fiber from a viewpoint of intensity | strength, and it is more preferable that it is carbon fiber.

Examples of aramid fibers include Kevlar.
The fiber is not particularly limited in its form, and examples thereof include fiber woven fabric and unidirectional fiber.
Basis weight of the fibers is preferably from 140~200g / m ^2.

  Examples of commercially available fibers include carbon fiber T-300 manufactured by Toray Industries, Inc. and carbon fiber HTA grade manufactured by Toho Rayon.

  The method for combining the epoxy resin composition for fiber-reinforced composite material with the reinforcing fiber is not particularly limited. For example, a method of impregnating and applying an epoxy resin composition for a fiber reinforced composite material to a reinforcing fiber can be mentioned.

The fiber-reinforced prepreg of the present invention is not particularly limited for its production. For example, a method of impregnating a reinforcing fiber with an epoxy resin composition for a fiber reinforced composite material and a method of laminating a plurality of reinforcing fibers impregnated with an epoxy resin composition for a fiber reinforced composite material can be mentioned.
When the fiber is impregnated with the epoxy resin composition for fiber reinforced composite material, for example, either a wet method using a solvent or a hot melt method which is a solventless method can be employed.
When manufacturing a prepreg by a wet method, the epoxy resin composition for fiber-reinforced composite materials is dissolved in a solvent to prepare a varnish, and then impregnated.
Examples of the solvent used in preparing the varnish include alcohols such as methanol, ethanol and propanol; ketones such as methyl ethyl ketone (MEK).
It is preferable that the usage-amount of a solvent is 100-200 mass parts with respect to 100 mass parts of solid content of the epoxy resin composition for fiber reinforced composite materials from a viewpoint that drying time can be shortened.

  In the fiber-reinforced prepreg of the present invention, the content of the matrix resin is 30 to 50% by mass in the fiber-reinforced prepreg from the viewpoint of excellent self-adhesiveness, workability, appearance quality, and mechanical properties of the fiber-reinforced prepreg. It is preferable that it is 35 to 45% by mass.

The method for using the fiber-reinforced prepreg of the present invention is not particularly limited, and examples thereof include a method of curing the fiber-reinforced prepreg of the present invention as it is and a method of semi-curing and further curing the fiber-reinforced prepreg of the present invention.
The conditions for curing are the same as described above.

  The fiber-reinforced prepreg of the present invention is not particularly limited for its use. By curing the fiber-reinforced prepreg of the present invention, for example, a conventionally known fiber-reinforced composite material can be obtained. Specifically, for example, motorcycle parts such as motorcycle frames, cowls, and fenders; doors, bonnets, tailgates, side fenders, side panels, fenders, energy absorbing members, trunk lids, hard tops, side mirror covers, spoilers, diffusers, Automotive parts such as ski carriers, engine cylinder covers, engine hoods, chassis, air spoilers, propeller shafts; vehicle outer panels such as leading vehicle noses, roofs, side panels, doors, truck covers, side skirts; luggage racks, seats, etc. Railway vehicle parts: interior, wing inner panels, outer panels, roofs, floors, etc., aero parts such as side skirts for automobiles and motorcycles; window frames, luggage racks, seats, floor panels Aircraft parts such as wings, propellers, fuselage, etc .; Cases for notebook computers, mobile phones, etc .; Medical uses such as X-ray cassettes and top boards; Applications for acoustic products such as flat speaker panels and speaker cones; Golf heads, face plates, Sports equipment applications such as snowboards, surfboards, protectors, etc .; general industrial applications such as leaf springs, windmill blades, elevators (籠 panels, doors).

Moreover, a fiber reinforced composite material can be produced by laminating the fiber reinforced prepreg of the present invention and another member (for example, a honeycomb core). Examples of the fiber reinforced composite material that can be produced by laminating the fiber reinforced prepreg of the present invention and other members include a honeycomb sandwich panel.
The fiber-reinforced prepreg of the present invention can form a fillet having high self-adhesive strength, high toughness and excellent strength by using the composition of the present invention, tackiness, drapeability, and productivity. Excellent workability.
Moreover, the fiber reinforced composite material obtained from the fiber reinforced prepreg of the present invention can be bonded to other members without using an adhesive, has excellent smoothness of the fiber reinforced prepreg, and has little porosity (surface irregularities). Excellent appearance and surface properties.

Next, the honeycomb sandwich panel of the present invention will be described below.
The honeycomb sandwich panel of the present invention is
The fiber-reinforced prepreg of the present invention and the honeycomb core are laminated and cured.

  The fiber reinforced prepreg used in the honeycomb sandwich panel of the present invention is not particularly limited as long as it is the fiber reinforced prepreg of the present invention. Since the fiber reinforced prepreg used in the honeycomb sandwich panel of the present invention has excellent adhesiveness, it can be bonded to the honeycomb core without using an adhesive, and a high strength fillet can be formed. .

  Further, the honeycomb core used in the honeycomb sandwich panel of the present invention is not particularly limited. Examples thereof include at least one selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.

  The size of the hexagonal column of the honeycomb core honeycomb structure is not particularly limited, and the honeycomb core has a cell size length of 1/8 to 3/8 inch from the viewpoint of strength and weight reduction. .

The honeycomb sandwich panel of the present invention is not particularly limited for its production.
An example of a method for manufacturing a honeycomb sandwich panel of the present invention will be described below with reference to the accompanying drawings.
FIG. 3 is a perspective view schematically showing an example of the honeycomb sandwich panel of the present invention.
FIG. 4 is a cross-sectional view schematically showing an example of a cross section obtained by cutting the honeycomb sandwich panel in parallel with the side surfaces of the prisms of the honeycomb core. Part a of FIG. 4 is a honeycomb sandwich panel to which a fiber reinforced prepreg formed from a conventional resin composition for a prepreg sheet is bonded. Part b of FIG. 4 is an example of the honeycomb sandwich panel of the present invention.

  In FIG. 3, the honeycomb sandwich panel 1 is obtained by bonding a fiber reinforced prepreg 10 and a honeycomb core 11. More specifically, the honeycomb sandwich panel 1 is formed by bonding a fiber reinforced prepreg 10 formed of the composition of the present invention to one or both of the end portions 12 of the honeycomb core 11 having a honeycomb structure, and press-bonding from both ends. It can be produced by heat curing with, for example.

4, when a fiber reinforced prepreg using the conventional composition as an epoxy resin composition for a fiber reinforced composite material is used, as shown in part a of FIG. 4, the fiber reinforced prepreg 10 and the honeycomb core are heated and cured. 11 evenly, all the epoxy resin composition for fiber reinforced composite material falls to the lower surface portion 13 ′ and no fillet is formed on the upper surface portion 13, or the fiber reinforced prepreg 10 and the honeycomb core 11 are partially formed. There may be a gap on the bonding surface.
On the other hand, when the composition of the present invention is used, the fiber-reinforced prepreg 10 and the honeycomb core 11 are completely bonded as shown in part b of FIG. 4, and the fiber-reinforced prepreg is used for the fiber-reinforced composite material. An appropriate amount of the composition can be present in the fiber-reinforced prepreg without causing the epoxy resin composition to flow out excessively and the resin component to disappear from the fiber-reinforced prepreg.
Accordingly, the upper fillet 14 can complete curing while maintaining an appropriate shape. Also, the lower fillet 14 ′ is formed by the surface tension when the viscosity once decreases on the lower surface, and the epoxy resin composition for fiber-reinforced composite material is appropriately held to complete the curing.

  The heating temperature at the time of bonding the fiber reinforced prepreg 10 and the honeycomb core 11 is preferably 50 to 200 ° C, more preferably 70 to 190 ° C, from the viewpoint of heat resistance of the cured product.

The curing conditions for bonding the fiber reinforced prepreg 10 and the honeycomb core 11 are 2 to 5 ° C./min, pressurization is 2.5 to 4.0 kg / cm ² , and the temperature is raised to 150 to 185 ° C. One preferred embodiment is a method in which the temperature is maintained at 150 to 185 ° C. for 1 to 2 hours and then lowered to room temperature at 2 to 5 ° C./min.
By such a method, the honeycomb sandwich panel of the present invention can be manufactured.

The honeycomb sandwich panel of the present invention is excellent in fillet formability, fillet strength, mechanical strength, and workability.
The honeycomb sandwich panel of the present invention can be used as a structural material for aircraft and automobiles, for example.

The conventional fiber reinforced prepreg has a problem that when the honeycomb core and the fiber reinforced prepreg are directly bonded, the strength of the fillet formed on the joint surface between the honeycomb core and the fiber reinforced prepreg is low and the toughness is inferior. there were.
On the other hand, in the honeycomb sandwich panel of the present invention, the cured product of the composition has high toughness because the fiber reinforced prepreg as a raw material uses the composition of the present invention as the matrix resin composition. Can do. This high toughness contributes to increasing the strength of the fillet.
This is because, in the composition of the present invention, the epoxy resin (a3), the epoxy resin (a2), and the curing agent (C) are pre-reacted so that the resulting epoxy resin (a3) has an epoxy resin ( Since it has the molecular skeleton of a1), it can have excellent affinity for the epoxy resin (a1), and as a result, it is presumed that the toughness of the resulting cured product is high.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

1. Preparation of epoxy resin (a3) by preliminary reaction The components shown in the preliminary reaction column of Table 1 below are used in the quantitative ratios shown in the preliminary reaction column of Table 1, and these mixtures are brought to 150 ° C. with stirring. Epoxy resin (a3) was prepared by heating and reacting for 4 hours for pre-reaction. The epoxy resin (a3) obtained by the preliminary reaction was used for the preparation of the following epoxy resin composition for fiber-reinforced composite materials.

2. Preparation of epoxy resin composition for fiber reinforced composite material The epoxy resin (a3) obtained above and the components shown in Table 1 (curing agent (C) and The components used in the preliminary reaction were removed.) And the mixture was mixed while heating to 130 ° C. to obtain a mixture. Next, after the obtained mixture was cooled to 70 ° C., the curing agent (C) was added in the amount shown in Table 1 (unit: parts by mass), mixed while heating to 70 ° C., and fiber reinforced. An epoxy resin composition for composite materials was prepared.

3. Preparation of Fiber Reinforced Prepreg Each composition obtained was applied onto release paper using a reverse roll coater to prepare a resin film. Next, two resin films obtained were used, two resin films, and carbon fibers [Torayca (registered trademark) T-700, manufactured by Toray Industries, Inc., tensile elastic modulus, arranged in one direction in a sheet shape. 230 GPa, and so on. And the two sides of the carbon fiber so as to be sandwiched between two resin films. Thereafter, the resin was impregnated with carbon fiber by heating and pressing to obtain a unidirectional prepreg with a basis weight of 196 ± 5 g / cm ² and a mass fraction of the matrix resin of 40%.

4). Production of Honeycomb Sandwich Panel Using the obtained composition, two prepregs were produced in the same manner as described above, and between the obtained prepregs, an aramid substrate honeycomb core (SAH-1 / 8 inch-8.0) was prepared. , 12.7 mm thick, manufactured by Showa Aircraft Co., Ltd.) under a pressure of 3.2 kgf / cm ² , the temperature was raised from 70 ° C. to 180 ° C. at a heating rate of 2 ° C./min and cured at 180 ° C. for 2 hours A honeycomb sandwich panel was obtained.

5. Evaluation The tackiness and draping property of the obtained fiber reinforced prepreg were evaluated. The results are shown in Table 1.
Further, the obtained composition was cured under the following conditions to obtain a cured product, the fracture toughness value of the cured product was measured, and the morphology after curing was observed. The results are shown in Table 1.
Further, the CDP peel strength of the obtained honeycomb sandwich panel was measured. The results are shown in Table 1.

(1) Tackiness Two sheets of the obtained prepreg were laminated to form a plate shape of about 0.5 mm, and then the presence or absence of tack (adhesive strength) was evaluated by finger touch in an environment of 25 ° C.
As the evaluation criteria for tackiness, the tack of the prepregs of Comparative Examples 1 and 2 was set to 5, and the better, the higher the numerical value.

(2) Drapability Each of the obtained prepregs was bent by hand, and the presence or absence of drape (the suppleness of the prepreg) was evaluated by finger touch in a 25 ° C environment.
The evaluation criteria for the drapability were set to 5 for the prepregs of Comparative Examples 1 and 2, and the better, the higher the numerical value.

(3) Fracture toughness value (K _1C )
A resin plate having a thickness of 7 mm is formed on the release paper with each of the obtained compositions, and this is placed in an autoclave and heated from 70 ° C. to 180 ° C. at a heating rate of 2 ° C./min. Curing was performed at 0 ° C. for 2 hours to prepare a cured product having a thickness of 7 mm.
A test sample is prepared from the obtained cured product in accordance with ASTM D-5045-99, and the fracture toughness value (stress intensity factor, unit: MPa · m ^1/2 ) is measured at room temperature (25 ° C.). did.

(4) Morphology after curing The cross section of the destroyed test sample after the measurement of the above fracture toughness value was measured with a transmission electron microscope (TEM, trade name: model M-800, manufactured by Hitachi, Ltd. The same shall apply hereinafter). And observed.
As a result of observation, regarding the morphology of the cured product, a case where both the epoxy resin (A) and the thermoplastic resin (B) formed a continuous phase was defined as “co-continuous”.
Moreover, the case where the morphology of the cured product has a reverse sea island structure in which the island phase (dispersed phase) of the epoxy resin (A) is dispersed in the continuous phase of the thermoplastic resin (B) was defined as “reverse sea island”.
The cured product has a morphology in which both the epoxy resin (A) and the thermoplastic resin (B) form a continuous phase, and the thermoplastic resin (B) has an island phase of the epoxy resin (A) in the continuous phase. The case where the (dispersed phase) has a reverse sea island structure in which it is dispersed was defined as “reverse sea island and co-continuous”.

Moreover, the photograph of the cross section of the test sample of the comparative example 1 image | photographed by 5,000 times with the transmission electron microscope is shown in FIG.
FIG. 2 shows a photograph of a cross section of the test sample of Example 1 taken with a transmission electron microscope at a magnification of 5,000 times.

(5) CDP Peeling Strength Each of the obtained honeycomb sandwich panels was subjected to a peeling test (Climbing Drum Peel test) according to ASTM D1781.

Each component shown in Table 1 is as follows.
Epoxy resin (a4): Triglycidyl-p-aminophenol, trade name MY-0510, manufactured by Huntsman Advanced Materials, Inc. Epoxy resin (a1) used in the preliminary reaction and epoxy contained as a component of the composition Resin (a1): Bisphenol F diglycidyl ether represented by the following formula (1), trade name jER806, manufactured by Japan Epoxy Resin Co., Ltd.

Thermoplastic resin (B): polyethersulfone resin (average particle size 50 μm), trade name Sumika Excel PES5003P, manufactured by Sumitomo Chemical Co., Ltd. Epoxy resin (a2) used in preliminary reaction and epoxy contained as a component of the composition Resin (a2): Solid bisphenol A type epoxy resin, weight average molecular weight 20,000, average particle diameter 15 μm, trade name YDF-020N, manufactured by Tohto Kasei Co., Ltd., curing agent (C) used in preliminary reaction and composition components Curing agent (C) contained as: 3,3′-diaminodiphenyl sulfone, trade name 3,3′-DDS, manufactured by Huntsman Advanced Materials

As is apparent from the results shown in Table 1, Comparative Example 1 in which the composition did not contain the epoxy resin (a3) had a low fracture toughness value and CDP peel strength.
In contrast, Examples 1 and 2 had higher fracture toughness values than Comparative Example 1, and were excellent in the toughness of the cured product.
In Examples 1 and 2, the CDP peel strength was higher than that of Comparative Example 1, and the fillet strength was high.
This is because in the cured products obtained from the compositions of Examples 1 and 2, the epoxy resin (a3) has a high affinity for the epoxy resin (A), and the epoxy resin (a3) is contained in the epoxy resin (A). It is considered that dissolution and / or dispersion is facilitated and the particle diameter of the epoxy resin (a3) is reduced.
In the cured product obtained from the composition of the present invention, the particle size of the epoxy resin (a3) is small, and the epoxy resin (a3) is easily dissolved and / or dispersed in the epoxy resin (A). This is shown in FIG.
In FIG. 2, (B) which is a dark color part is a thermoplastic resin (B), (A) which is a gray part is an epoxy resin (A), and is a white island phase in the epoxy resin (A) (a3 ) Represents an epoxy resin (a3). The morphology of the cured product of Example 1 has the co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and the reverse sea island structure of the thermoplastic resin (B), and the continuous phase of the epoxy resin (A). An epoxy resin (a3) is dispersed therein.
On the other hand, in FIG. 1, (B) which is a dark color part is a thermoplastic resin (B), and (A) which is a gray part is a white island phase in the epoxy resin (A) and the epoxy resin (A) ( a3) represents an epoxy resin (a3). The morphology of the cured product of Comparative Example 1 has an inverted sea-island structure of a continuous phase of the thermoplastic resin (B) and an island phase of the epoxy resin (A), and the epoxy resin (A3) is contained in the epoxy resin (A). The island phase is dispersed.
Comparing the size of the epoxy resin (a3) in FIGS. 1 and 2, it can be seen that the epoxy resin (a3) in FIG. 2 is smaller than that in FIG. 1 and is more dispersed.
Thus, in the composition of the present invention, the epoxy resin (a3) has a high affinity for the epoxy resin (A), and the epoxy resin (a3) is sufficiently dispersed and / or in the epoxy resin (A). By being compatible, it becomes a cured product having high toughness, and is considered to effectively relieve external stress.

FIG. 1 is a photograph of a cross-section of a test sample of Comparative Example 1, taken at a magnification of 5,000 with a transmission electron microscope. FIG. 2 is a photograph of a cross section of the test sample of Example 1 taken at a magnification of 5,000 with a transmission electron microscope. FIG. 3 is a perspective view schematically showing an example of the honeycomb sandwich panel of the present invention. FIG. 4 is a cross-sectional view schematically showing an example of a cross section obtained by cutting the honeycomb sandwich panel in parallel with the side surfaces of the prisms of the honeycomb core.

Explanation of symbols

(A) Epoxy resin (A)
(B) Thermoplastic resin (B)
(A2) Epoxy resin (a3)
DESCRIPTION OF SYMBOLS 1 Honeycomb sandwich panel 10 Fiber reinforced prepreg 11 Honeycomb core 12 End part 13 Upper surface part 13 'Lower surface part 14 Upper fillet 14' Lower fillet a Conventional honeycomb sandwich panel b Honeycomb sandwich panel of this invention c Cell size

Claims (19)

Using an epoxy resin (a1) having a weight average molecular weight of 1,000 or less, an epoxy resin (a2) having a weight average molecular weight of 10,000 to 100,000, and a curing agent (C),
An epoxy resin (a3) obtained by pre-reacting a part of the epoxy resin (a1), a part or all of the epoxy resin (a2) and a part of the curing agent (C), and the epoxy An epoxy resin (A) containing the remainder of the resin (a1);
A thermoplastic resin (B);
Containing the remainder of the curing agent (C),
The epoxy resin composition for fiber-reinforced composite materials, wherein the cured form has a co-continuous phase of the epoxy resin (A) and the thermoplastic resin (B) and / or a continuous phase of the thermoplastic resin (B). The epoxy resin (A) further includes a trifunctional or higher functional epoxy resin (a4),
The fiber reinforcement according to claim 1, wherein the amount of the epoxy resin (a4) is 30 to 90 parts by mass in 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). Epoxy resin composition for composite materials. Used in the preliminary reaction,
The amount of a part of the epoxy resin (a1) is 2 to 20 parts by mass in 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3),
A part or all of the epoxy resin (a2) is 2 to 20 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3).
A part of the curing agent (C) is used in an amount of 0.2 of the epoxy group contained in a part of the epoxy resin (a1) and a part or all of the epoxy resin (a2) used in the preliminary reaction. The epoxy resin composition for fiber-reinforced composite materials according to claim 1 or 2, wherein the amount is equivalent to -0.4 equivalents.   The fiber reinforced composite material according to any one of claims 1 to 3, wherein a molecular skeleton of the epoxy resin (a2) is at least one selected from the group consisting of bisphenol A type, bisphenol F type and copolymers thereof. Epoxy resin composition.   The remaining amount of the epoxy resin (a1) is 1 to 68 parts by mass in 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). The epoxy resin composition for fiber-reinforced composite materials according to any one of the above.   The amount obtained by removing the epoxy resin (a2) used in the preliminary reaction from the epoxy resin (a2) is 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). 0 to 18 parts by mass The epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 5.   The amount of the epoxy resin (a3) used in the preliminary reaction excluding a part of the curing agent (C) is the epoxy resin (A) 100 excluding the epoxy resin (a2) and the epoxy resin (a3). It is 4-40 mass parts with respect to a mass part, The epoxy resin composition for fiber reinforced composite materials in any one of Claims 1-6.   The epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 7, wherein the thermoplastic resin (B) has a reactive functional group at a molecular end.   The fiber according to any one of claims 1 to 8, wherein the thermoplastic resin (B) is a polyethersulfone resin particle and / or a polyetherimide resin particle, and the average particle diameter of the particle is 200 µm or less. Epoxy resin composition for reinforced composite materials.   The amount of the thermoplastic resin (B) is 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). The epoxy resin composition for fiber-reinforced composite materials according to any one of the above.   The hardener (C) used in the epoxy resin composition for fiber-reinforced composite materials according to any one of claims 1 to 10 is diaminodiphenyl sulfone and / or a latent hardener. An epoxy resin composition for fiber-reinforced composite materials according to claim 1.   The amount of the curing agent (C) is 20 to 60 parts by mass with respect to 100 parts by mass of the epoxy resin (A) excluding the epoxy resin (a2) and the epoxy resin (a3). The epoxy resin composition for fiber-reinforced composite materials according to any one of the above.   The epoxy resin composition for fiber-reinforced composite materials according to any one of claims 1 to 12, wherein the minimum viscosity by dynamic viscoelasticity measurement at a temperature rising rate of 2 ° C / min is 10 to 150 Pa · s. The epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 13, wherein a fracture toughness value measured in accordance with ASTM D5045-99 after curing is 2.0 MPa · m ^1/2 or more. .   A fiber-reinforced prepreg obtained by combining the epoxy resin composition for fiber-reinforced composite material according to claim 1 with a reinforcing fiber as a matrix resin.   The fiber-reinforced prepreg according to claim 15, wherein the content of the matrix resin is 30 to 50% by mass in the fiber-reinforced prepreg.   The fiber-reinforced prepreg according to claim 15 or 16, wherein the reinforcing fibers are carbon fibers.   A honeycomb sandwich panel obtained by laminating and curing the fiber-reinforced prepreg according to any one of claims 15 to 17 and a honeycomb core.   The honeycomb sandwich panel according to claim 18, wherein the honeycomb core is at least one selected from the group consisting of an aramid honeycomb, an aluminum honeycomb, a paper honeycomb, and a glass honeycomb.

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